Method of enhancing the varietal coloration of whole fruit



UNITED STATES PATENT OFFICE METHOD OF ENHANCING THE VARIETAL COLORATION OF WHOLE FRUIT Jagan N. Sharma, Riverside, Calif., assignor to Food Machinery Corporation, San Jose, Calif., a corporation of Delaware No Drawing. Application November 12, 1934,

Serial No. 752,699

8 Claims. (Cl. 99-103) This invention relates to improved methods of templates 2, method in which the fruit is subenhancing the varietal color of fruit provided jected to sequential contact with two reagents, with water-repellent and/or oily outer skin, parneither of which is capable of individually imticularly citrus fruit. parting a desired coloration to the'fruit. but

It has been pointed out heretofore that attracwhich react within the outer layers of the skin tiveness and coloration of citrus fruits is not an or peel with the formation of a desired coloring absolute criterion of the juice content, sugar substance The reagents may well be dye intercontent, degree of maturity, etc. Due to variamediates having the property of penetrating into tions in weather conditions during critical pethe outer skin or peel. l0 riods of growth, or due to cultivation or lack It is an object of this invention, therefore, to 10' of cultivation during such periods, the fruit may disclose and provide a method of imparting an not develop the ideally characteristic varietal enhanced varietal coloring to fruit provided with color although such fruit has reached maturity water-repellent surfaces.

and has an entirely acceptable and desirable juice Another object is to disclose and provide a l5 and sugar content. The purchasing public is method of imparting an enhanced varietal colorinfluenced by the visual appearance of the fruit ing to whole fruit provided with water-repellent in purchasing the same. As a result, large quanskins or peels without the use of actual dyes. tities of fruit which are entirely satisfactory as to Another object is to provide a method of imjuice and sugar content, are sold at prices below parting an enhanced varietal coloring to whole the market price simply because the characterfruit without the necessity of using baths or re- 20 istic varietal color had not been developed to a agents at temperatures above 100 F. required extent. r A still further object is to disclose and provide This invention is particularly directed toward a method of imparting an enhanced varietal color a novel method of treating citrus fruit having a to whole fruit provided with water-repellent satisfactory juice and sugar content, for the purskins or peels whereby large quantities of fruit-25 pose of enhancing their varietal color to the may be treated with relatively small volumes of end that the fruit may assume their proper potreating solution. sition in the markets of the world. These and other objects, uses, advantages and Inimparting a desired varietal coloration to adaptations of the invention will become appar- 3 fruit provided with oily and/or water-repellent cut to those skilled in the art from the subseskin, it isdesired that the color become an inquent description of a preferred manner of pertegral part of the skin and permeate the exterior forming the method of this invention and of portions of the skin so as to be substantially ircertain modifications thereof. removable therefrom. The use of colloidal solu- In carryingout the process of this invention.

tions of oil-soluble dyes has been disclosed in my it is not necessary that the fruit, such as citrus 35 co-pending application Serial No. 712,831, filed fruit, be first washed although preliminary wash- February 24, 1934, such oil-soluble dyes impreging is of advantage in that dirt and other impurinating the oily, waxy and water-repellent skins ties which may otherwise impair the appearance of the fruit. of the fruit, are removed. The washed fruit In the prior methods, temperatures above 100 need not be contacted with an antiseptic or ster 40 F. were used in the treating bath in order to perilizlng or mold-inhibiting agent as the reagents mit the required action to take place within a used in accordance with this invention exert a commercially feasible and economical time. In suitable and efficient sterilizing and mold-inaccordance with the present. invention, however, hibiting action. .The washed fruit may or may oil-soluble dyes are not used, thereby permitting not be preliminarily sorted or graded as to color 45 smaller volumes of treating agents to be used and and/or size. Preliminary grading for color is deconcomitantly higher concentrations. The quansirable, however, as the entire treating operation tity or proportion of oil-soluble dye in the treatmay then be carried out with the production of ing bath heretofore used hasbeen relatively small. fruit of more uniform final color. I

Moreover, the method of the present invention For purposes of illustration, the intermediates 5 can be carried out at normal atmospheric temmay consist of beta naphthol and diazotized xyli-' peratures, thereby obviating the necessity of dine. The first bath containing the beta naphmaintaining accurate temperature control during thol may consist of water to which sodium hythe performance of the process. dro'xide has been added. In making up anaque- Generally stated, the present invention conous solution, the ingredients may be used in the 55 proportion of grams of beta naphthol to 1000 grams of 15% sodium hydroxide solution. Alcohol or other organic solvent may be present in the bath, but in general such solvents are not desirable as they increase the cost and sometimes cause burning of the fruit. The diazotized intermediates or beta naphthylamine may be used in any desired concentration and either diluted with organic solvents or with water. Variation in concentration of intermediates may materially influence the time that the fruit need be maintained in contact therewith to cause the intermediate to penetrate into the peel or skin.

The fruit which it is desired to treat are dipped, sprayed or otherwise brought into contact with the beta naphthol solution, such contact being maintained for a period of from but a few seconds to 1 minute or more. The bath need not be heated and is preferably maintained at normal atmospheric temperatures. I

The fruit may then be rinsed with water to remove excess beta naphthol and passed through a second bath of intermediate capable of reaction or coupling with the first intermediate. The intermediates used in performing this process are preferably oil-soluble or soluble in solvents capable of impregnating or penetrating the waterrepellent, oily and/or waxy skins or peels of the fruit or such intermediates may consist of an acid salt which, upon solution in water, hy-

drolyzes to form an oil-soluble intermediate con-- stituent.

The fruit, after first being contacted with the beta naphthol solution and being rinsed, can then be passed into a bath containing diazotized xylidine in which bath they are maintained for a period of from 2 or 3 seconds to a period of about 1 minute. Upon being removed from this secondary bath, it will be found that the fruit are of an enhanced orange color.

After contact with the secondary intermediate, the fruit is preferably washed and scrubbed for the purpose of removing any dye which may have formed directly on the surface of the fruit. The customary steps of drying, waxing and polishing may then be carried out upon the fruit, or the secondary intermediate bath may contain a small quantity of waxy material in solution or suspension.

Various intermediates capable of coupling with the production of colors suitable for the treatment of citrus fruits are available. The beta. naphthol mentioned hereinabove may be coupled with diazotized aniline, for example, instead of diazotized xylidine. Other examples include:

Diazotized amino azo xylene coupled with mixed beta naphthol and phenol Diazotized amino azo benzene coupled with beta naphthyl'amine I v Diazotized amino azo toluene coupled with beta naphthylamine Diazotized amino azo xylene coupled with beta naphthylamine fruit from decay,

The precise sequence in which the fruit is subjected to theaction of the intermediates referred to hereinabove is not essential, that is to say, that when naphthylamine and diazotized aniline are used, the fruit may be contacted with the naphthylamine either before or after being brought into contact with the diazotized aniline. When using naphthylamine, it is recommended that about 25 grams thereof be used with 1000 cc. of 0.25 normal nitric acid.

In view of the fact that relatively high concentrations of the intermediates may be employed in the treating baths, very short times of contact may be employed. For example, the average time of contact of the fruit with a bath of intermediates need notexceed minute and shorter times often suflice. These short timesof contact do not impair the keeping qualities of the fruit and as a result, withering or shrinkage of the treated fruit upon storage is not accelerated. In view of the sterilizing effect obtained, it is not necessary to subject the fruit to the action of a separate bath containing mold-inhibiting or mold-retarding ingredients. As the treatment may be (and preferably is) carried out at relatively low atmospheric temperatures, the cost of equipment is reduced and the process does not necessitate the careful control which characterized some of the prior methods. A relatively small treating unit is gapable of handling extremely large quantities of ruit.

It will be seen, therefore, that a simple and very effective method of treating fruit has been provided, such method simultaneously enhancing the varietal color of the fruit and sterilizing the fruit so that the development of decay caused by the various types of molds and fungi is effectively prevented. Moreover, the process is capable of being used at normal atmospheric temperatures and preferably at temperatures below 100 F. with concentrated treating agents so that the size of the installments and cost thereof is kept at a minimum. Although particular couplings of intermediates have been disclosed, other dye intermediates capable of reacting with one another in such manner as to produce a dye of the desired shade or tone, may be used. Generally stated, diazotized intermediates, beta naphthol and beta naphthylamine are the preferred intermediates for use in this process.

All such changes and modifications as come within the scope of the appended claims are embraced thereby.

I claim:

I. In a method of enhancing the varietal color of whole fruit and simultaneously protecting said the steps of contacting whole fruit with a diazotized intermediate, removing fruit from such contact, and then contacting the l fruit with a bath containing beta naphthol whereby an enhanced varietal color is imparted to substantially the entire surface area of the fruit.

2. In a method of enhancing the varietal color of whole fruit and simultaneously protecting said fruit from decay, the steps of contacting whole fruit with a diazotized intermediate, removing fruit from such contact, then contacting the fruit with a bath containing beta naphthylamine, and

then rinsing the fruit whereby an enhancedvarietal color is imparted to substantially the entire surface area of the fruit.

3. In a method of enhancing the varietal color 'ing whole citrus fruit with a diazotized intermedianaoeo ate, removing fruit from such contact, and then contacting the fruit with another intermediate adapted to react with the diazotized intermediate to form a desired dye throughout the surface area of the fruit whereby the varietal color of the fruit is enhanced, said contacting being carried out at normal fruit-treating temperatures.

4. In a method of enhancing the varietal color of whole fruit, the steps of contacting whole fruit with a diazotized intermediate for a period of time sufiicient to cause said intermediate to penetrate into the peel of the fruit, removing fruit from such contact, and then contacting the fruit with another intermediate adapted to react-with the diazotized intermediate to form a desired dye throughout the surface area of the fruit whereby the varietal color of the fruit is enhanced.

5. In a method of enhancing the varietal color of whole fruit, the steps of contacting whole fruit with a diazotized intermediate for a period of time sufiicient to cause said intermediate to penetratc into the peel of the fruit, removing fruit from such contact, then contacting the fruit with another intermediate adapted to react with the diazotized intermediate to form a desired dye throughout the surface area of the fruit whereby the varietal color of the fruit is enhanced, and then subjecting the fruit to cleaning and waxing operations.

6. In a method of enhancing the varietal color of whole citrus fruit, the steps of contacting whole citrus fruit with one intermediate, removing fruit from such contact, and then contacting the fruit with another intermediate, one of said intermediates being of the diazotized type and the other being adapted to react with the diazotized type to form a dye throughout the surface of the fruit whereby the varietal color of the fruit is enhanced.

7. In a method of enhancing the varietal color of whole citrus fruit, the steps of contacting whole citrus fruit with a diazotized intermediate, removing fruit from such contact, and then contacting the fruit with a bath containing a mixture of naphthol and phenol whereby an enhanced varietal color is imparted to substantially the entire surface area of the fruit.

8. In a method of enhancing the varietal color of whole citrus fruit, the steps of contacting whole citrus fruit with beta naphtholfremoving fruit from such contact, and then contacting the fruit with a bath containing diazotized xylidine whereby a dye substance adapted to enhance the varietal color of fruit is formed over the entire surface area of the fruit.

JAGAN N. SEAR. 

